The present invention is related to multicolor printing involving impact printing with a movable inked ribbon and more particularly to control circuitry for coordinating the motion of the inked ribbon with the relative movement of a print head and a record medium, and with the impact printing action of the print head on such medium.
This application is related to copending commonly assigned U.S. patent application Ser. No. 399,129 filed July 16, 1982 and Ser. No. 399,216 filed July 19, 1982 and Ser. No. 399,130 filed July 16, 1982 and Ser. No. 494,350 filed May 13, 1983. The disclosure of these related applications is hereby incorporated by reference.
The use of multicolor inked ribbons in printers, such as for example dot matrix printers, for various printing applications is known. The trend in this field has been to higher printing speeds, higher density and more varied color combinations. This has been particularly true in applications involving graphic display. This trend has led to problems in achieving ribbon movement in a plurality of directions and coordinating this movement with the motion of the print head carriage and the printing action of individually controllable dot print wires in the print head. Additionally, with bidirectional printing in which printed dot elements are interlaced or overprinted to achieve color mixing, it is necessary to control ribbon movement vertically as well as horizontally. Prior art arrangements have suffered in their inability to perform these functions very quickly and precisely with a high degree of reliability and control.
Accordingly, one object of this invention applicable to impact printing involving an inked ribbon comprising bands of different colors of the same or differing width running the length of the ribbon, is to provide an improved arrangement for printing symbols in a wide variety of color combinations while taking into account the extent to which different colors may differ in their frequency of use.
Accordingly, a further object of this invention is to provide an improved control for multicolor printing of symbols.
A further object of this invention is to provide an improved arrangement for controlling ribbon movement vertically as well as horizontally.
A further object of this invention is to provide an improved arrangement for achieving multicolored ribbon movement in desired directions while coordinating this movement with the motion of the print head and the individually controllable dot print wires in the print head of a matrix printer.
A further object of this invention is an improved arrangement to control incremental stepping of a ribbon vertically in either direction to present a multiplicity of bands of a ribbon to the print line.
A further object of this invention is to provide an improved arrangement for selectively changing the pattern of bands to be presented to the print line.
Briefly, in accordance with one embodiment of the invention there is provided an arrangement for printing symbols along a line of print in a combination of desired colors corresponding to parallel bands of different colored ribbon movable along the line of print involving a movable print head comprising a plurality of print wires which may be selectively actuated to impact a desired color band of the ribbon against a record medium. Means are provided for moving said ribbon in response to a first set of control pulses along a print line at a desired rate. Means responsive to a second set of control pulses are provided to increment the ribbon vertically in either direction to present a desired color of said ribbon to said print line at a desired column location along said print line. Means responsive to a third set of control pulses are provided to move the print head along said print line to said desired column position. Means responsive to a fourth set of control pulses are provided to activate selective print wires in a direction to impact said color band of said ribbon against said record medium to effect printing of dots corresponding to said activated print wires in said desired color on said record medium. The means for incrementing the ribbon vertically and for positioning it in front of the print head at the desired color band of ribbon comprises a ribbon shift shutter receiving the ribbon moving across the line of print coupled for movement with the print head. A pair of lift levers carrying ribbon guide rollers at each end are positioned at opposite ends of said print line and adapted for rotational motion at one end remote from said print line about an axis. Means for moving said shift shutter vertically in response to control pulses comprise a stepping motor and associated lead screw and nut arrangement located at opposite ends of said print line and coupled to respective other ends of associated lift levers. The stepping motors operate respective lead screws to increment an associated lead screw nut vertically. A bail extending across said print line is coupled at each end to a respective lead screw nut. The shift shutter is coupled to said bail for movement along the line of print in response to print head movement and in the vertical direction in response to vertical motion of the lead screw nut whereby the desired ribbon bands are indexed vertically to the desired color at the desired column location in front of the print head to effect impact printing by activated print wires of symbols of desired color.